886 research outputs found

    Using Abrupt Changes in Magnetic Susceptibility within Type-II Superconductors to Explore Global Decoherence Phenomena

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    A phenomenon of a periodic staircase of macroscopic jumps in the admitted magnetic field has been observed, as the magnitude of an externally applied magnetic field is smoothly increased or decreased upon a superconducting (SC) loop of type II niobium-titanium wire which is coated with a non-superconducting layer of copper. Large temperature spikes were observed to occur simultaneously with the jumps, suggesting brief transitions to the normal state, caused by en masse motions of Abrikosov vortices. An experiment that exploits this phenomenon to explore the global decoherence of a large superconducting system will be discussed, and preliminary data will be presented. Though further experimentation is required to determine the actual decoherence rate across the superconducting system, multiple classical processes are ruled out, suggesting that jumps in magnetic flux are fully quantum mechanical processes which may correspond to large group velocities within the global Cooper pair wavefunction.Comment: 13 pages, 4 figures, part of proceedings for FQMT 2011 conference in Prague, Czech Republi

    Quantum incompressibility of a falling Rydberg atom, and a gravitationally-induced charge separation effect in superconducting systems

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    Freely falling point-like objects converge towards the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous, and possesses a tidal component. The free fall of an extended quantum object such as a hydrogen atom prepared in a high principal-quantum-number stretch state, i.e., a circular Rydberg atom, is predicted to fall more slowly that a classical point-like object, when both objects are dropped from the same height from above the Earth. This indicates that, apart from "quantum jumps," the atom exhibits a kind of "quantum incompressibility" during free fall in inhomogeneous, tidal gravitational fields like those of the Earth. A superconducting ring-like system with a persistent current circulating around it behaves like the circular Rydberg atom during free fall. Like the electronic wavefunction of the freely falling atom, the Cooper-pair wavefunction is "quantum incompressible." The ions of the ionic lattice of the superconductor, however, are not "quantum incompressible," since they do not possess a globally coherent quantum phase. The resulting difference during free fall in the response of the nonlocalizable Cooper pairs of electrons and the localizable ions to inhomogeneous gravitational fields is predicted to lead to a charge separation effect, which in turn leads to a large repulsive Coulomb force that opposes the convergence caused by the tidal, attractive gravitational force on the superconducting system. A "Cavendish-like" experiment is proposed for observing the charge separation effect induced by inhomogeneous gravitational fields in a superconducting circuit. This experiment would demonstrate the existence of a novel coupling between gravity and electricity via macroscopically coherent quantum matter.Comment: `2nd Vienna Symposium for the Foundations of Modern Physics' Festschrift MS for Foundations of Physic

    Can a charged ring levitate a neutral, polarizable object? Can Earnshaw's Theorem be extended to such objects?

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    Stable electrostatic levitation and trapping of a neutral, polarizable object by a charged ring is shown to be theoretically impossible. Earnshaw's Theorem precludes the existence of such a stable, neutral particle trap.Comment: 11 pages, 1 figur

    A Marine Incursion in the Lower Pennsylvanian Tynemouth Creek Formation, Canada:Implications for Paleogeography, Stratigraphy and Paleoecology

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    We document the occurrence of a marine bed, and its associated biota, in the Lower Pennsylvanian (Langsettian) Tynemouth Creek Formation of New Brunswick, and discuss its implications for paleogeography, stratigraphy, and paleoecology. This is only the second marine interval found in the entire Pennsylvanian fill of the Maritimes Basin of Canada, the other being recently found in the broadly same-age Joggins Formation of Nova Scotia. Evidence for the new marine transgression comprises an echinoderm-rich limestone that infills irregularities on a vertic paleosol surface within the distal facies of a syntectonic fluvial megafan formed under a seasonally dry tropical climate. Gray, platy ostracod-rich shales and wave-rippled sandstone beds that directly overlie the marine limestone contain trace fossils characteristic of the Mermia Ichnofacies, upright woody trees, and adpressed megafloras. This association represents bay-fills fringed by freshwater coastal forests dominated by pteridosperms, cordaites, and other enigmatic plants traditionally attributed to dryland/upland habitats. The fossil site demonstrates that marine transgressions extended farther into the interior of Pangea than has previously been documented, and may allow correlation of the Tynemouth Creek and Joggins Formations with broadly coeval European successions near the level of the Gastrioceras subcrenatum and G. listeri marine bands. It also helps explain the close similarity of faunas between the Maritimes Basin and other paleotropical basins, if transgressions facilitated migration of marine taxa into the continental interior

    Legal Procedure - Collateral Estoppel Doctrine - Application of Collateral Estoppel from an Administrative Hearing to a Civil Action

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    The Pennsylvania Supreme Court held that, given the fast and informal nature of unemployment compensation proceedings, as well as the economic risk in those actions, a factual finding made during an unemployment compensation hearing should not be afforded preclusive effect in a subsequent civil action brought by the same employee. Rue v. K-Mart Corp., 713 A.2d 82 (Pa. 1998)

    Recent Developments in Pennsylvania Constitutional Law

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    Structural investigations of fibers and films of poly(p-phenylene benzobisthiazole).

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    Polymer Science and EngineeringDoctor of Philosophy (PhD

    Plasma Turbulence in the Local Bubble

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    Turbulence in the Local Bubble could play an important role in the thermodynamics of the gas that is there. The best astronomical technique for measuring turbulence in astrophysical plasmas is radio scintillation. Measurements of the level of scattering to the nearby pulsar B0950+08 by Philips and Clegg in 1992 showed a markedly lower value for the line-of-sight averaged turbulent intensity parameter thanisobservedforotherpulsars,consistentwithradiowavepropagationthroughahighlyrarefiedplasma.Inthispaper,wediscusstheobservationalprogressthathasbeenmadesincethattime.Atpresent,therearefourpulsars(B0950+08,B1133+16,J04374715,andB0809+74)whoselinesofsightseemtoliemainlywithinthelocalbubble.Themeandensitiesandlineofsightcomponentsoftheinterstellarmagneticfieldalongtheselinesofsightaresmallerthannominalvaluesforpulsars,butnotbyasmuchexpected.Threeofthefourpulsarsalsohavemeasurementsofinterstellarscintillation.Thevalueoftheparameter than is observed for other pulsars, consistent with radio wave propagation through a highly rarefied plasma. In this paper, we discuss the observational progress that has been made since that time. At present, there are four pulsars (B0950+08, B1133+16, J0437-4715, and B0809+74) whose lines of sight seem to lie mainly within the local bubble. The mean densities and line of sight components of the interstellar magnetic field along these lines of sight are smaller than nominal values for pulsars, but not by as much expected. Three of the four pulsars also have measurements of interstellar scintillation. The value of the parameter is smaller than normal for two of them, but is completely nominal for the third. This inconclusive status of affairs could be improved by measurements and analysis of ``arcs'' in ``secondary spectra'' of pulsars.Comment: Submitted to Space Science Reviews as contribution to Proceedings of ISSI (International Space Science Institute) workshop "From the Heliosphere to the Local Bubble". Refereed version accepted for publicatio
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